For electrical switches for automobiles, it is known that the movable contact points connected to the operating element can be designed as spring tongues which are stamped out of a contact plate. Such a switch is described, for example, in German Patent No. 4,039,984. With the known switch, the operating element is shifted parallel to the plane of the stationary contacts, so that electrical connection between the movable contacts and the stationary contacts is achieved due to displacement in the desired order.
One disadvantage of the known switch is that the movable spring tongues are not attached to the operating element until after the forming of the operating element. An additional disadvantage of the known switch is that due to the abrasive movement, the movable contact areas maintain contact with the insulating compound in which the stationary contacts are embedded as well as the stationary contacts themselves. In addition, during the transition to contacting or separating from a stationary contact, the contact surface between the moving contact and the stationary contact changes relatively slowly, while at the same time, part of the movable contact remains in contact with the insulating compound surrounding the stationary contact. The resulting electric arc causes heating of the surrounding insulating compound and possible soiling of contacts, formed due to the insulating compound, is burned into the movable contact.
The object of the invention is to improve on the switching performance of the switch of the known generic type, so that both load currents and control currents can be switched by this switch.
The invention consists in principle of joining the spring tongues together through a plastic socket and also anchoring the plastic socket in the switch housing. This prevents a shifting movement parallel to the contact plane of the stationary contacts. The change in contact closure between stationary and movable contacts takes place instead with the help of a mechanical control, which is driven by a suitable operation linkage. In this way it is possible to avoid a transfer of the movable contacts from the stationary contacts to the insulating compound surrounding the stationary contacts, so that soiling of the contacts is prevented, and a clean separation of the contacts from one another during the switching operation is possible. Furthermore, it is possible to simplify the casting mold of the switch housing, since the plastic socket with the spring tongues and the housing itself are produced in separate casting operations. The design of the switch according to the present invention also makes it possible to test the contact closure of the movable contacts step by step before the anchoring of the plastic socket in the switch housing, as discussed further below.
According to one preferred embodiment, all contact tongues running essentially parallel to one another are punched out together in one punching operation, wherein they are still mechanically connected to one another. Then the contact tongues that are connected to one another by webs are fixed opposite one another by injection of a common plastic holder, and finally, in a third step, the spring tongues are electrically separated from one another in the desired manner by cutting the connecting webs open subsequently.
One disclosed method of connecting the movable contacts to stationary plug-in connections takes advantage of the fact that the spring tongues open into plug-in connections that are molded in one piece and, together with the spring tongues, are punched out of the contact plate. It may be preferred to strengthen the plug-in connections by designing them as contact blades which are formed by folding corresponding projections on the spring tongues. In a preferred embodiment, the plug-in connections are anchored in the switch housing at the same time by the engagement of the plug-in connections through openings in the switch housing.
To achieve the result that the movable contacts on the contact tongues establish contact with the stationary contacts as a result of the movement of an operating element in suitable operating sequence, another embodiment of the present invention proposes modification of the radial cam, wherein it is thus possible to change the operating sequence even with the same movement curve of the operating element. The present invention is particularly suitable for activating the movable contacts by means of an actuating lever of a steering column switch. Through the movement of the actuating lever, the radial cams assigned to the individual spring tongues act on the spring tongues and thus create the predetermined contact closure as a function of the position of the actuating lever. If the sequence of contact closure is to be variable as a function of the predetermined positions of the actuating lever, so in another embodiment of the invention, one need only select the suitable radial cams in order to obtain the desired switch sequence through the position of the actuating lever.
The design of the actuating lever can be simplified through the introduction of the radial cam regardless of the design of the actuating lever. This measure can be used not only with respect to a single spring tongue, but also on several or even all spring tongues. To simplify the assembly of the driver rod in the switch, it is proposed in another embodiment of the invention that the driver rods be connected to one another by parallel plastic spring arms, which are in turn connected to one another. Thus, the totality of all the driver rods serving to operate a switch are combined in a single component, which simplifies the assembly of the switch through the driver rod, since now only the common cross piece must be anchored in the switch housing.
The resulting construction essentially looks like a comb, with the driver rods projecting at right angles to the plane of the comb at the end of the comb teeth. Since the switch housings are to be equipped automatically with these combs, the teeth of the comb must be prevented from becoming entangled in the shipping container. For this purpose, rake-like projections are provided on the comb teeth, extending into the plane of the comb and thus filling up the interspaces between the comb teeth. This makes it impossible for the teeth belonging to different combs to become entangled.
In order to be able to anchor the spring tongues in the switch housing jointly in one operation, the plastic socket is inserted into a guide opening in the switch housing parallel to the plane of the spring tongues. It is thus necessary only to insert the plastic socket automatically into the switch housing in a first direction perpendicular to the plane of the spring tongues and then engage it with the housing in a second direction perpendicular to the plane of the spring tongues.
To also ensure the creation of terminal contacts on the housing with this insertion movement of the spring tongues at the same time, the blade shaped plug-in connections extend in the insertion direction of the plastic socket. The advantage of such a design is that with the insertion of the plastic socket into the switch housing, the terminal contacts are also simultaneously inserted in to the respective openings, so that at the end of the end of the movement of the spring tongues in the aforementioned direction, the terminal contacts protrude from the switch housing.
By designing the plastic socket and the cross piece such that they extend from above in the same direction are inserted in the open switch housing, automatic assembly of the switch elements is greatly simplified, and thus can be assembled by the same automatic equipment.
From what has been said, it is apparent that with the present invention easy insertion of the aforementioned switch elements into the switch housing should be possible at the same time. For this purpose certain process steps are disclosed; these steps are also used at the same time to test the movable contacts in their contact position inside the switch. Therefore, in principle, the method is to insert the plastic socket provided with the movable contacts into the housing, checking on whether all the movable contacts are a distance from the respective stationary contacts in this position. This rules out the possibility of inserting contact leads, where at least one spring arm in the latter position reaches the respective stationary contact.
Then the plastic socket with the individual spring tongues is inserted a certain distance, and then one determines whether in this position all the movable contacts are in contact with the stationary contacts. If one of the spring tongues is bent so far that no contact is made in this condition, then the entire contact lead is not allowed for assembly. The plastic socket is subsequently engaged in the switch housing in a direction in which the contact pressure of the supported movable contacts is increased by a certain amount. After carrying out these steps, one can be certain that the switch will open and close properly depending on the position of the respective driver rod.
This method is thus summarized as follows:
1. Assembly step 1 includes the insertion of the plastic socket with springs/tongues (i.e., the "ZUS spring.revreaction. or "assembled spring") into the base plate. PA0 Subsequent testing to determine whether all contacts are still open. If a contact is closed, a spring arm must be bent downward. PA0 2. Testing for contact closure includes pressing the ZUS spring a defined distance in the engaged direction. PA0 Then testing is made to determine if for whether all contacts are closed. If a contact is not closed, a spring arm must be bent upward. PA0 3. Assembly step 2 includes engaging the ZUS spring PA0 The spring arms are prestressed, which creates the contact force.